Make gets() deprecated.

gets is already deprecated in glibc. Others with __warnattr are not deprecated.

Change-Id: I80a276d2b5964630218be47f1c94b146c0d31151
diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index b04aa24..eb578f5 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -266,7 +266,7 @@
 
 #ifndef __AUDIT__
 #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 201112L
-char* gets(char*) __warnattr("gets is very unsafe; consider using fgets");
+char* gets(char*) __attribute__((deprecated("gets is very unsafe; consider using fgets")));
 #endif
 int sprintf(char* __restrict, const char* __restrict, ...)
     __printflike(2, 3) __warnattr("sprintf is often misused; please use snprintf");